Magnetic thread cases and oscillating looptakers



April 13, 1965 G. F. c. BURKE ETAL MAGNETIC THREAD CASES AND OSCILLATINGLOOP'IAKERS Filed Nov. 13, 1962 5 SheetsSheet l Inventors: Gearye FCBur/te J/ton C'op/thorne .53 (he/r flUo/"ney WM) April 1955 ca. F. c.BURKE ETAL 3,177,832

MAGNETIC- THREAD CASES AND OSCILLATING LOOPTAKERS Filed Nov. 13, 1962 5Sheets-Sheet 2 April 13, 1965 G. F. c. BURKE ETAL 3,177,832

MAGNETIC THREAD CASES AND OSCILLATING LOOPTAKERS Filed Nov. 15, 1962 5Sheets-Sheet 3 April 13, 1965 G. F. c. BURKE ETAL 3,177,832

MAGNETIC THREAD CASES AND OSCILLATING LOOPTAKERS Filed Nov. 13, 1962 5Sheets-Sheet 4 April 1965 s. F. c. BURKE ETAL 3,177,832

MAGNETIC THREAD CASES AND OSCILLATING LOOPTAKERS Filed Nov. 13, 1962 5Sheets-Sheet 5 United States Patent 3,177,832 IVIAGNETIC AD CASESANDVGSCHLATHJG LUGPTAKERS 7 George F. Q. Burke, Beverly, and Alton R.Copithorne, Rowley, Mass, assignors to United Shoe MachineryCorporation, Boston, Mass, a corporation of New Jerse y Filed Nov. 13,1962, Ser. No. 237,258

8 (Jlairns. (Cl. 112-33) This invention relates generally toimprovements in look stitch shoe outsole sewing machines or stitchersand more particularly to a looptaker and cooperating thread caseconstruction especially useful in such machines.

Conventional stitchers of most modern types generally include rotarylooptakers for interlocking the needle thread with a locking thread bypassing a loop of needle thread about a stationarythread case in whichis maintained a supply of locking thread. Such a looptaker is drivencontinuously two or three revolutions during each sewing cycle andduring one revolution of each cycle carries the needle loop.

Major disadvantages of conventional looptaker arrangements include acomplex shape which in order to be eltective must be formed with a highdegree of accuracy and accordingly results in a high manufacturing cost.In addition, the high speed of rotation tends to minimize the usefullife of looptakers which, being expensive to manufacture and to replace,results in a machine which is expensive to maintain. The thread casesassociated with such looptakers are also complex in form and subject torapid wear thereby adding to the cost of maintenance.

Equally important is the fact that the common ratio of three revolutionsof the looptaker during each sewing cycle is an important limitingfactor upon attainable sewing speeds. Another disadvantage ofconventional thread case constructions is that in replenishing thelocking thread supply a hot bobbin must be replacedand handled by theoperator thereby increasing the time required for locking .thread supplyreplenishment and consequently resultingin lowered efficiency of machineutilization.

It is accordingly an object of the present invention to reduce themanufacturing cost ,of looptakers suitable for lock stitch shoe sewingmachines.

Aniadditional object is to provide readily manufactured, easilyreplaceable parts most subjectto wear in looptakers so that the cost ofmachine maintenance may be effectively reduced. .7 Y

Still another object is to provide a looptaker construction in whichportions of the machine instrumentalities coming into contact withthethread do not-require lubrication and hence maybe. operated drywithout danger pf soiling work pieces and without shortening theiruseful ife.

Still another object is to provide a looptakerconstructionof minimummass suitable for oscillatory movement at high sewing speeds.

tant feature of the invention resides in a looptaker having aplow-shaped beak which engages a spread-open needle loop and carries itpart way. about a thread case as thread is supplied by a thread hook andtakeup of generally conventional design. Mounted within the path of thehook are a pair of annular thread guiding members or rings one of whichis fixed and the other hinged so that it may be opened to receive thethread case which is mounted between the'rings. The thread case issomewhat loosely mounted between the guide rings and thus adapted. to bemoved slightly by the needle loop in passing about the case. The guiderings are of magnetic material and formed with conical interior surfaceswhich are notched to receive a loosely fitted stem of the thread casethereby to prevent angular displace ment of the case by the passage ofthe thread. The thread case, according to another feature of theinvention, is of light nonmagnetic material and provided with a seriesof inserted magnets so that the attraction of the magnets to the ringspositions the case to facilitate the passage of the needle loop.

Other features of the invention including the form of the plow-shapedhook for economy of manufacture and ease of replacement and theprovision of a heat source to facilitate the use of certain types ofcoated threads will be readily appreciated from the following detaileddescription of an illustrative embodiment of the invention taken inconnection with the accompanying drawings, in which FIG. 1 is afragmentary view in perspective as seen from the front and right andpartly in exploded relationship of a looptaker and thread case accordingto the present invention;

FIG. 2 is a view in front elevation of some of the parts shown in FIG.1, particularly depicting the looptaker at the completion of a needleloop carrying motion;

FIG. 3 is a view in cross section taken along the line III-III of FIG.2, showing the mountingof the locking thread case within a pair ofannular thread guiding members; FIG. 4 is a view partially in crosssection taken along the line IV-IV of FIG. 2 and depicting the positionof a needle thread loop on the looptaker;

FIG. 5 is a greatly enlarged view showing the interior construction of astem forming part of the thread case;

FIG. 6 is a view in cross section depiciting the stem of FIG. 5, its.interior construction and its relationship Yet another object is toprovide a removable thread case 'structureadapted to being economicallyproduced so that the replenishment of the locking. thread supply may beaccomplished quickly by replacing the empty thread case withonecontaining a new supply. of thread.

A still further object is to provide thread guiding case andincludinginexpensive means for retaining the thread case in position forneedle loopsto be passe 'aboutit. H

In the achievementof theforegoing objects an importo the thread case andto the annular thread guides;

FIG. 7 is a view of the parts depicted in FIG. 6 as seenrfrom the pointof exit of the locking threadfrom the locking thread case; i

FIG. 8 is a fragmentary schematic view of a sewing machine showing atakeup and other thread handling instrumentalities in addition to thelooptaker construction, according to the present invention;

FIG. 9 is a schematic view in perspective in which portions of threadguiding members are broken. away to show the thread case and in whichthe beak of the loop taker carrying a needle loop is depicted insuccessive angular positions;

FIGS. 10 and 11 are fragmentary views of the beak of thelooptaker'showing successive stages in the disengagement of the needleloop from the beak of the looptaker.

The present invention is embodied in a heavily con- 7 structed lockstitch shoe sewing machine including a members associated with thelooptaker and the thread awl 14 the workpiece, which may be'thought ofas coma prising the outsole 16 and the' welt 18 of a shoe, rests upon awork support 29 and is clamped by a presser foot 22. Otherconventionalinstrumentalities of the machine for manipulating a needle thread 24include a looper 26, a thread storing hook 28, a takeup 30,,and' frontand rear thread locks indicated at 52 and 34 respectively. Actingbetween the thread locks is a thread measuring arrangement of usualdesign including a thread measuring finger 36.. g V

. According to the present invention, the needle thread 24 isinterlocked with a lockin thread 38 by a looptaker 49 of simple, noveland economical construction. The looptaker 4t) is oscillated about theaxis. of a shaft 42 and includes a plow-shaped beak 44 which travelsover an arcuate path about a fixed inner guide ring 46 and an outerguide ring 48. A thread case indicated generally at 50 is supportedloosely between the guide rings 46, 48 and encloses a quantity'oflocking thread or cop 51 preferably in the form of the thread package,disclosed in an application for United States Letters Patent Serial No.156,316, filed December 1, 1961, in the names of George F. C. Burke andRobert W. Bradley and now abandoned.

Connections for imparting an oscillatory movement to the looptaker 49are driven from a sewing shaft 52 which is journaled in the frame anddriven one revolution for each stitch in conventional manner. Mitergears 54 and 56 keyed respectively to the sewing shaft 52 and to a camshaft 53 are included among the driving connections for the looptaker40V The shaft 58 which is journaled in the frame 10 has keyed to it apair of conjugate cams 60 and 62 the contours of which are engagedrespectively by follower rolls 64 and 66 rotatably supported on two armsof a'lever 68. The lever 68 is pivoted on a headed shaft 70 pinned inthe frame 10 and is formed with a generally vertical arm the lower endof which terminates in a gear sector 72 engaging the teeth of a pinion74 formed integral with the shaft 42. The front end surface of thepinion 74 is slotted to receive an integral key 76 on the looptaker 4%which is also pierced for a retaining screw '78 passing loosely throughthe looptaker and into engagement with the threads of a tapped hole inthe shaft 42. a

The thread case 56 is formed of nonmagnetic material with conical threadengagingsurfaces intersecting and defining a ridge 82 which serves'toseparate the legs of each loop of needle thread as it is passed over thecase. The case 50 isof a material which offers the advantages of lowweight, high abrasion resistance and dimensional stability. Thesequalities are available in a variety of well-known synthetic polymericmaterials which may be inexpensively molded to finished dimensions.Enclosed within the body of the thread case 50 preferably as moldedinserts are two sets of permanent magnets 84, 86, all preferablypolarized in the same direction, which assist in positioning thecase-between the guides 46 and 48. The thread is brought out from theinside of the case through a hollow stem 88 containing a leaf springfriction 90 secured to the stem by screws 91. The stem itself ispreferably molded into the body of the case. The rings 46 and 48 arenotched at 92 loosely to embrace the stem 88 and thus prevent the casefrom being angularly displaced by the passage of the thread but leavingsufiicient space to permit the needle thread to pass. between the stemand the Walls of the notches. The case itself is received between therings 46, 48 which are of magnetic material, by opening the ring 48which for this purpose 192 for passage of the locking thread and alsowith an opening 104 (FIGS. 3 and 9) for observing the remaining supplyof locking thread and to permit the introduction of heated air to softenthe coating normally applied to the thread. To prevent Withdrawal of theshield from the interior of the case a thin retaining plate 195 issecured to the guide ring 48.

Heated air is introduced into the inside of the cop 51 through theopening 104'by means of a nozzle 106 (FIG. 8) in communication with aconduit 107 secured by a clamp 198 to the frame of the machine. Insidethe conduit 1&7 is a thermostatically-controlled, electricallyheatedcartridge 112 and the conduit is connected through a'fiexible pipe 114to a source of air under pressure. Both the quantity of air and thetemperature setting of the thermostat may be regulated to suit theparticular type of coating applied to the thread. The heated air thusintroduced permits even thread coated with highly adhesive waxes to besmoothly Withdrawn from the cop.

The operation of the present looptaker arrangement will best beunderstood from a description of the passage of a single loop of threadabout the thread case 50. At the time that the needle 12 withdrawscarrying the loop of needle thread the beak 44 is in the solid lineposition of FIG. 9 below the needle loop as it is opened by a loopspreader 116.

The movement of the thread over the thread case 50, star-ting with thepick up of the needle loop by the beak 44 and ending with its releasefrom the beak will best be understood from a description of thedisposition of the needle thread in successive positions of the beak, asseen in FIG. 9, and identified by letters A, B, C, D and E. In thepresent machine the needle loop is passed over the thread case withoutbeing twisted so that the standing leg of the loop, rearward side of thethread case while the running leg, designated by the symbol R, passesover the front of the case, the standing leg being thatpart of thethread running between the beak and the stitch hole from the last stitchand :the running leg being the part of the thread running between thebeak and the stitch hole and on to the thread is hinged at 94,- and issecured in operative position by a X-Shaped clamp 96 provided with aknurled clamp screw 98, about which it may be moved between inoperativeposition (FIG. 1) and operative position (FIG. 2).

The cop 51 is received within the case 50 in a cupshaped shield 100 ofthin nonmagnetic resilient metal such as phosphor bronze and removablyretained inside the thread case. The shield is formed with an aperturesupply.

As seen in FIG. 2, the plane of the beak 44 defines a hook angle X witha radial plane passing through the axis of the shaft 42 and the point ofintersection of the beak with an upstanding horn 120 which, with ashoulder 122, best seen in FIG. 9, limits entry of the beak into theloop of the needle thread. The hook angle is typically in the order of60 to assure retention of the needle loop by the beak. An included angleY defined between the two arms of the beak, as seen in FIG. 8, ispreferably equal to between 70 and and the size of this angle alsointeracts with the magnitude of the hook angle already mentioned as willlater be explained.

Returning to FIG. 9 it will be seen that in moving between positions Aand B a horizontal portion of the needle loop extending between theneedle 12 and the loop spreader 116 is picked up by the beak and becauseof the direction of the hook angle X is pulled inwardly toward the axisof movement of the beak. In traveling between the positions B and C thelooptaker causes the partial unwrapping of the needle thread from thebarb of the needle and durnig this time the loop spreader 116 is movedrearwardly to relinquish-complete control over the needle loop to thebeak 44. The motion of the beak from positions B to C causes the needleloop to expand in size and for this purpose a part of the threadrequired by the standing leg is supplied .by the thread hook 28 whilethe remainder of the thread is yielded by the takeup 30. At the positionD of the beak the needle loop is completely free of both the needle 12and of the loop spreader 116 and an intermediate point on both thestanding and running legs has engaged inwardly sloping surfaces of theguide rings 46, 48 respectively, so that the legs are directed closertogether and into contact with designated by the symbol S, passes acrossthe It will also be observed that the beak 44 is formed with a forwardlyextending appendage 124 for controlling the progressive wrap of thethread about the cross section of the beak as the beak moves from theposition B to the position E. Shortly after the position D is passed,the needle loop reaches its maximum extension and thereafter no morethread need be yielded by the take-up 30. The legs of the loop havingbeen brought into engagement with the thread case between the guiderings 4-6 and 4-3 are divided by the ridge S2 and begin to flow over therearward and forward faces of the thread case. As this flow over thefront and rear faces of the thread case occurs, the legs of the needleloop first pass between the magnets 34 and the guide rings 46 and 48causing the case 50 to be depressed slightly from its normal position.As the case is thus depressed its'position is maintained by theattraction between the magnets 86 and the guide rings while the casepivots about the stem 38 in the notches of the guide rings. Thereafterthe legs of the needle loop are drawn by. the beak between the magnets86 and the guide rings as the magnets 84 are ragain'attracted to theguide rings and the thread case rises to its normal position. As thebeak reaches the position E, the legs of the needle loop which atposition B were wrapped about approximately one quarter of the cross.

section of each arm of the beak, are now wrapped about" approximatelythree quarters of the cross section. At this point in the operatingcycle of the machine the movement of the beak is arrested and thetake-up 3t) begin to contract the needle loop thus shortening therunning leg R which passes completely across the front face of thethread case. Since the stitch hole is approximately in line with theridge 82, as seen in FIG. 8, the running leg having completed itspassage across the front face of the thread case is then reoriented withrespect to the beak 44 from the dash line position to the solid lineposition, shown in FIG. 10. After the length of the running leg has beenshortened to the point that it is disposed in essentially a straightline running from the stitch hole to a point near the horn 120 on thebeak, continued retraction of the thread by the take-up 30 causes thepoint of contact of the running leg Rat the beak to slide downwardlytoward the tip of the beak, as shown in FIG. 10. The horizontal portionof the needle loop bridging the eak between the legs of the loop isshortened by further retraction of thread and the points of engagementof the loop on the beak correspondingly slide closer together. As thepoints of contact reach the inside apex of the loop the legs pressagainst the horizontal portion and the loop is thereby snapped ol'r thepoint of the beak and thus freed, as seen in FIG. 11. After being freedfrom the beak the needle loop continues to be retracted and is thusdrawn between the thread case and the guide ring 46 until it movescompletely out of engagement with the thread case, having beeninterlocked with the locking thread from the cop 51, as shown in theincomplete stitch depicted in FIG. 2. Thereafter the continued pull ofthe take-up upon the needle thread causes the interlocked portions ofthe two threads to be set as a complete stitch in the thickness of theoutsole 16.

The inter-relation between the hook angle X and the included angle Y isrealized from considering the function of the beak 44 in picking up theloop at the position B with reliability and in releasing the loop in theposition E under conditions of permissible thread tension. An increasein the hook angle X beyond the indicated 60 value improves thereliability of loop pickup and retention because of the fact that thetip of the beak is tilted upwardly in the position B. However, in theposition E a hook angle of 60 which provides adequate reliability forcarrying the loop offers a suitable angle of approach to the running legR so that disengagement of the loop from the beak may be achievedwithout excessive thread tension. The position of the beak in its loopreleasing position is effected by the necessary relationship of the axisof the thread case with the point of penetrationof the work by theneedle which in turn provides clearance for the work piece withoutexcessive extension of the needle loop.

The included angle Y may be reduced below the approximate shown in FIG.8 and this reduction in the size of the included angle enhances theperformance of the beak in' entering theloop and retaining it until thebeak reaches the position E. However, a reduction below the 70 to rangeindicated as acceptable for the included angle greatly increases thetension required to cause slippage of the needle loop oif the beak. Onthe other hand a substantialincrease above the acceptable range of theincluded angle causes the loop tobe wedged off the beak under workingtension before the position E is reached and accordingly causes themissing of stitches and reduces the reliability of the machine.

Having thus described our invention what we claim as new and desire tosecure by Letters Patent of the United States is:

1. A sewing machine having a curved hook needle for penetrating aleather work piece at a sewing point and for withdrawing from the workpiece carrying a loop of needle thread, a take-up for yielding thread tothe needle during its withdrawal from the workpiece and during furtherexpansion of the needle loop, in combination with a pair of notchedthread guiding members of magnetic material, a thread case forcontaining a supply of lock: ing thread, means for magneticallyattracting the thread case to the thread guiding members, a hollow stemon the thread case entering the notches of the guiding members andformed with a passage for the locking thread, and' means for carryingthe loop of needle thread about the case.

2. A sewing machine having a curved hook needle for penetrating aleather work piece at a sewing point and for withdrawing from the workpiece carrying a loop of needle thread, a sewing shaft, a take-up foryielding thread to the needle during its withdrawal from the workpieceand during further expansion of the needle loop, in combination with apair of generally annular thread guiding members of magnetic material, anonmagnetic thread case, magnetic inserts in the case attracted to thethread guiding members, and means for carrying the loop of needle threadabout the case including a plow-shaped beak and connections to thesewing shaft for oscillating the beak over a path around a part of theperiphery of the guide members.

3. A sewing machine having a curved hook needle for penetrating aleather work piece at a sewing point and for withdrawing from the workpiece carrying a needle thread loop having two legs, a sewing shaft, atake-up for yielding thread for enlargement of the needle loop andretracting thread to contract the needle loop, in combination with apair of generally annular thread guiding members, a thread case retainedagainst rotation and loosely supported between the thread guidingmembers, a plow-shaped needle loop-carrying beak having interiorsurfaces upon which both legs of the needle loop slip toward the tip ofthe beak for disengagement of the loop from the beak when the beak is ina loop-shedding posi tion and the loop is contracted by the take-up andconnections to the sewing shaft for oscillating the beak from aloop-entering to the loop-shedding position.

4. A sewing machine having a curved hook needle for penetrating aleather work piece at a sewing point and for withdrawing from the workpiece carrying a needle thread loop having two legs, a sewing shaft, atake-up for yieldin gthread for enlargement of the needle loop andretracting thread to contract the needle loop, in combination with apair of generally annular thread guiding members, a thread case retainedagainst rotation, loosely supported between the thread guiding membersfor containing a supply of locking thread, a'plovwshapedj needle loopcarrying beak having an included angle of between 70' and 110* and apair of interior surfaces upon each of which one of the legs of theneedle loop slips toward the tip of the beak for disengagement of theloop from the beak when the beak is in a loop-shedding position and theloop is contracted by the take-up, and connections to the sewing shaftfor oscillating the beak from aloop-entering to the loop-sheddingposition. I

5. A sewing machine having a curvedv hook needle for penetrating aleather Work piece at a sewing point and for withdrawing from the workpiece carrying a loop of needle thread,'a sewing shaft, a take-up foryielding thread for enlargement of the needle loop and retracting threadto contract the needle loop, in combination with a pair of generallyannular thread guiding members, a thread case retained against rotationand loosely supported be tween the thread guiding members, a plow-shapedneedle loop-carrying beak movable about an axis and oriented relative tothe axis to present a hook angle of approximately 60 and'having interiorsurfaces upon which the needle loop slips toward the tip of thebeak fordisengagement from the beak when the beak is in a loop-shedding positionand the loop is contracted by the take-up, means on the beak forlimiting the entry of the beak into the needle loop, and connections tothe sewing shaft for oscillating the beak from a loop-entering to theloop-shedding position. g

6. A sewing machine having a curved hook needle for penetrating aleather work piece at a sewing point and for Withdrawing from the workpiece carrying a loop of needle thread, a sewing shaft, a take-up foryielding thread for enlargement of the needle loop and retracting threadto contract the needle loop, in combination with a pair of generallyannular notched magnetic thread guiding members, spaced apart inparallel relation along a common axis and formed withconcavecase-supporting surfacestandconvergent thread guiding surfaces, athread case for containing'a supply of locking thread, loosely supportedbetween the thread guiding members, means for retaining the case againstrotation including a hollow stem loosely entering the notches andthrough which the locking thread passes on its way to the work piece,magnetic inserts in the case attracted to the guiding members and meansfor carrying the needle loop about the thread case.

7. A sewing machine having a curved hook needle for for enlargement ofthe needle loop and retracting threadto contract the needle loop, incombination with a pair of generally annular notched magnetic threadguiding members, normally spaced apart in parallel relation along acommon axis and formed with concave case-supporting surfaces, a hingemounting for one of the guidingmembers, a latch retaining the hingedmember in parallel relation with the other, a thread case looselysupported between the thread guiding members, means including a hollowstem entering the notches in the guiding members for retaining the caseagainst rotation, magnetic inserts in the case attracted to the guidingmembers and means for carrying the needle loop about the thread case.

8. A sewing machine having a curved hook needle for penetrating aleather work piece at a sewing pointtand for withdrawing from the workpiece carrying a loop of needle thread, a sewing shaft, a take-up foryielding thread for enlargement of the needle loop and retracting 7thread to contract the needle loop, in combination with a pair ofmagnetic. thread guiding members, normally spaced apart in parallelrelation along a common axis, a thread case loosely supported betweenthe thread guiding members, means for retaining the case againstrotation,

two sets of similarly polarized magnetic inserts in the case attractedto the guiding members including a first set holding the case in normalposition and a second set. efiective while the needle loop isbeingpassed through the area of attraction of the first set, and means forcarrying the needle loop about the thread case.

References Cited by the Examiner UNlTED STATES PATENTS 1,063,987 6/13Mack 112-231 X 2,394,369 2/46 Colegrove 112-228 X 2,420,643 5/47Ashworth 112-38 2,543,475 2/51 Slodysko 112--229 v72,608,945 9/52Hagquist 112-181 2,763,227 9/56 Howard 11223l 2,784,690 3/57 Brandt112-l81 3,074,367 1/63 Habedank et a1. 112--228 JORDAN FRANKLIN, PrimaryExaminer.

3. A SEWING MACHINE HAVING A CURVED HOOK NEEDLE FOR PENETRATING ALEATHER WORK PIECE AT A SEWING POINT AND FOR WITHDRAWING FROM THE WORKPIECE CARRYING A NEEDLE THREAD LOOP HAVING TWO LEGS, A SEWING SHAFT, ATAKE-UP FOR YIELDING THREAD FOR ENLARGEMENT OF THE NEEDLE LOOP ANDRETRACTING THREAD TO CONTRACT THE NEEDLE LOOP, IN COMBINATION WITH APAIR OF GENERALLY ANNULAR THREAD GUIDING MEMBERS, A THREAD CASE RETAINEDAGAINST ROTATION AND LOOSELY SUPPORTED BETWEEN THE THREAD GUIDINGMEMBERS, A PLOW-SHAPED NEEDLE LOOP-CARRYING BEAK HAVING INTERIORSURFACES UPON WHICH BOTH LEGS OF THE NEEDLE LOOPS LIP TOWARD THE TIP OFTHE BEAK FOR DISENGAGEMENT OF THE LOOP FROM THE BEAK WHEN THE BEAK IS INA LOOP-SHEDDING POSITION AND THE LOOP IS CONTRACTED BY THE TAKE-UP ANDCON-